Muang district, Thailand
Muang district, Thailand

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Prietzel J.,TU Munich | Dumig A.,TU Munich | Wu Y.,CAS Chengdu Institute of Mountain Hazards and Environment | Zhou J.,CAS Chengdu Institute of Mountain Hazards and Environment | Klysubun W.,111 University Avenue
Geochimica et Cosmochimica Acta | Year: 2013

Phosphorus (P) is a crucial element for life on Earth, and the bioavailability of P in terrestrial ecosystems, which is dependent on the soil P stock and its speciation, may limit ecosystem productivity and succession. In our study, for the first time a direct speciation of soil P in two glacier foreland chronosequences has been conducted using synchrotron-based X-ray Absorption Near-Edge Structure (XANES) spectroscopy. The chronosequences are located in the forefields of Hailuogou Glacier (Gongga Shan, China) and Damma Glacier (Swiss Alps). The age since deglaciation of the investigated soils ranges from 0 to 120. years at Hailuogou, and from 15 to >700. years at Damma. Differences in climate conditions (cooler at Damma, in contrast to Hailuogou precluding the establishment of forest in advanced ecosystem succession stages) and in the chemical composition of the parent material result in different soil contents of total P and Fe/Al oxyhydroxides, which are much smaller at Damma than at Hailuogou. Nevertheless, both chronosequences show similar trends of their topsoil P status with increasing soil age. Our study reveals a rapid change of topsoil P speciation in glacier retreat areas already during initial stages of pedogenesis: Initially dominating bedrock-derived apatite-P and Al-bound P is depleted; Fe-bound P and particularly organically-bound P is accumulated. Organic P strongly dominates in the topsoil of the mature soils outside the proglacial area of Damma Glacier (age 700-3000. years), and already 50. years after deglacation in the topsoil of the retreat area of Hailuogou Glacier. A key factor for the change in topsoil P speciation is the establishment of vegetation, resulting in soil organic matter (SOM) accumulation as well as accelerated soil acidification and apatite dissolution by organic acids, which are produced by SOM-degrading micro-organisms, mykorrhiza fungi, and plant roots. Particularly the succession of grassland to forest seems to accelerate the transformation of topsoil P from apatite-P into organic P. The conceptual model developed by Walker and Syers (1976) to explain long-term (millennial) changes of P speciation, availability, and turnover in soils and terrestrial ecosystems seems to be valid to describe short-term changes of P speciation and P availability in proglacial topsoils already within a century of initial soil formation. Because the apatite-depleted topsoil horizons in the young proglacial soils are shallow, the change of topsoil P speciation should not seriously affect P availability and the P acquisition strategy of adult trees, whose roots can easily access apatite-containing C horizons. In contrast, P acquisition strategies of fungi, micro-organisms and plants confined to the topsoil probably change from apatite dissolution to mineralization of organic P already within <3000. years in a proglacial ecosystem succession from bare soil to grassland (Damma Glacier Chronosequence) or even within <100. years in a proglacial ecosystem succession to forest (Hailuogou Glacier Chronosequence). © 2013 Elsevier Ltd.

Poo-Arporn Y.,111 University Avenue | Thachepan S.,Kasetsart University | Palangsuntikul R.,King Mongkut's University of Technology Thonburi
Journal of Synchrotron Radiation | Year: 2015

Evidence of internal sulfate attack in field exposure was demonstrated by the damaged interior wall of a three-year-old house situated in Nakhon Ratchasima Province, Thailand. Partial distension of the mortar was clearly observed together with an expansion of a black substance. Removal of the black substance revealed a dense black layer. This layer was only found in the vicinity of the damaged area, suggesting that this black material is possibly involved in the wall cracking. By employing synchrotron-based X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) techniques, the unknown sample was chemically identified. The S 2p and O 1s XPS results mutually indicated the existence of sulfate species in the materials collected from the damaged area. The XANES results indicated the presence of ferrous (II) sulfate, confirming sulfate-induced expansion and cracking. The sulfate attack in the present case appeared to physically affect the structure whereas the chemical integrity at the molecular level of the calcium silicate hydrate phase was retained since there was a lack of spectroscopic evidence for calcium sulfate. It was speculated that internal sulfate probably originated from the contaminated aggregates used during the construction. The current findings would be beneficial for understanding the sulfate-attack mechanism as well as for future prevention against sulfate attack during construction. © 2015 International Union of Crystallography.

Songsiriritthigul C.,111 University Avenue | Buranabanyat B.,Suranaree University of Technology | Haltrich D.,University of Natural Resources and Life Sciences, Vienna | Yamabhai M.,Suranaree University of Technology
Microbial Cell Factories | Year: 2010

Background: Mannans are one of the key polymers in hemicellulose, a major component of lignocellulose. The Mannan endo-1,4-β-mannosidase or 1,4-β-D-mannanase (EC, commonly named β-mannanase, is an enzyme that can catalyze random hydrolysis of β-1,4-mannosidic linkages in the main chain of mannans, glucomannans and galactomannans. The enzyme has found a number of applications in different industries, including food, feed, pharmaceutical, pulp/paper industries, as well as gas well stimulation and pretreatment of lignocellulosic biomass for the production of second generation biofuel. Bacillus licheniformis is a Gram-positive endospore-forming microorganism that is generally non-pathogenic and has been used extensively for large-scale industrial production of various enzymes; however, there has been no previous report on the cloning and expression of mannan endo-1,4-β-mannosidase gene (manB) from B. licheniformis.Results: The mannan endo-1,4-β-mannosidase gene (manB), commonly known as β-mannanase, from Bacillus licheniformis strain DSM13 was cloned and overexpressed in Escherichia coli. The enzyme can be harvested from the cell lysate, periplasmic extract, or culture supernatant when using the pFLAG expression system. A total activity of approximately 50,000 units could be obtained from 1-l shake flask cultures. The recombinant enzyme was 6 × His-tagged at its C-terminus, and could be purified by one-step immobilized metal affinity chromatography (IMAC) to apparent homogeneity. The specific activity of the purified enzyme when using locust bean gum as substrate was 1672 ± 96 units/mg. The optimal pH of the enzyme was between pH 6.0 - 7.0; whereas the optimal temperature was at 50 - 60°C. The recombinant β-mannanase was stable within pH 5 - 12 after incubation for 30 min at 50°C, and within pH 6 - 9 after incubation at 50°C for 24 h. The enzyme was stable at temperatures up to 50°C with a half-life time of activity (τ1/2) of approximately 80 h at 50°C and pH 6.0. Analysis of hydrolytic products by thin layer chromatography revealed that the main products from the bioconversion of locus bean gum and mannan were various manno-oligosaccharide products (M2 - M6) and mannose.Conclusion: Our study demonstrates an efficient expression and secretion system for the production of a relatively thermo- and alkali-stable recombinant β-mannanase from B. licheniformis strain DSM13, suitable for various biotechnological applications. © 2010 Songsiriritthigul et al; licensee BioMed Central Ltd.

Songsiriritthigul C.,111 University Avenue | Lapboonrueng S.,111 University Avenue | Lapboonrueng S.,Suranaree University of Technology | Pechsrichuang P.,Suranaree University of Technology | And 2 more authors.
Bioresource Technology | Year: 2010

Chitinase (EC is an enzyme with multiple industrial applications. These include bioconversion of chitin waste, a highly resistant and abundant biopolymer from crustacean food industry, into glucosamine and chito-oligosaccharide value-added products. This paper reports on the expression of endochitinase (ChiA) from Bacillus licheniformis strain DSM8785 in E. coli and characterization of the recombinant enzyme. Recombinant ChiA could efficiently convert colloidal chitin to N-acetyl glucosamine and chitobiose at pH 4.0, 6.0 and 9.0 at 50 °C and retained its activity up to 3 days under these conditions, suggesting that this enzyme is suitable for bioconversion of chitin waste. © 2010 Elsevier Ltd. All rights reserved.

Kanjanachuchai S.,Chulalongkorn University | Euaruksakul C.,111 University Avenue
ACS Applied Materials and Interfaces | Year: 2013

Thermal decomposition of GaAs (111)A and (111)B surfaces in ultrahigh vacuum results in self-running Ga droplets. Although Ga droplets on the (111)B surface run in one main direction, those on the (111)A surface run in multiple directions, frequently taking sharp turns and swerving around pyramidal etch pits, leaving behind mixed smooth-triangular trails as a result of simultaneous in-plane driving and out-of-plane crystallographic etching. The droplet motion is partially guided by dislocation strain fields. The results hint at the possibilities of using subsurface dislocation network and prepatterned, etched surfaces to control metallic droplet motion on single-crystal semiconductor surfaces. © 2013 American Chemical Society.

Kanjanachuchai S.,Chulalongkorn University | Photongkam P.,111 University Avenue
Crystal Growth and Design | Year: 2015

Langmuir evaporation of stressed InSb and InAs (111)B crystals is studied using low-energy electron microscopy. The stress induces plastic relaxation by dislocation generation, whereas the evaporation results in self-running In droplets. The coexistence of in situ generated dislocations and self-running droplets allows droplet-dislocation interaction to be studied with minimal perturbation from other effects. The droplets run toward a preferred direction but are guided along dislocation lines before setting themself free once they accumulate mass and sufficient momentum to climb the energetic barrier posed by surface steps. The guiding effects are explained by surface stress which drives the mobile liquid along the dislocation line. This mechanism provides a means to control the direction of the self-running or self-propelled droplets, adding another degree of freedom to the growth and design of droplet-assisted micro- and nanostructures, for example, via interfacial dislocation network formed during heteroepitaxy. © 2014 American Chemical Society.

Kanjanachuchai S.,Chulalongkorn University | Euaruksakul C.,111 University Avenue
Crystal Growth and Design | Year: 2014

The nucleation and dynamics of multiple generations of In droplets formed from Langmuir evaporation of InP (001), (111)A, and (111)B surfaces are reported. In situ mirror electron microscopy reveals that the majority of first-generation, or mother, droplets break up immediately before they run from the nucleation sites, leaving behind daughter droplets and etch trails where more droplets emerge. These subsequent droplets grow with time and run once a critical size is reached. The breakup and running characteristics are explained in terms of crystallography, viscosity, chemical potential, and temperature and will likely affect the growth processes and designs of various droplet-catalyzed nanostructures and devices. © 2013 American Chemical Society.

Kulworawanichpong T.,111 University Avenue
International Journal of Electrical Power and Energy Systems | Year: 2010

This paper presents a simplified version of the well-known Newton-Raphson power-flow solution method, which is based on the current balance principle to formulate a set of nonlinear equations. Although there exist several powerful power flow solvers based on the standard Newton-Raphson (NR) method, their corresponding problem formulation is not simple due to the need for calculation of derivatives in their Jacobian matrix. The proposed method employs nonlinear current mismatch equations instead of the commonly-used power mismatches to simplify overall equation complexity. Derivation of Jacobian matrix's updating formulae is illustrated in comparison with those of the standard Newton-Raphson method. To demonstrate its use, a simple 3-bus power system was selected as a numerical example. The effectiveness of the proposed method was examined by computer simulations through five test systems: (1) 5-bus test system, (2) 6-bus test system, (3) 24-bus IEEE test system, (4) 30-bus IEEE test system and (5) 57-bus IEEE test system. Its convergence and calculation time were observed carefully and compared with solutions obtained by the standard NR power flow method. The results show that the proposed NR method spends less execution time than the standard method does with similar convergence characteristics. © 2009 Elsevier Ltd. All rights reserved.

Boonlakhorn J.,Khon Kaen University | Kidkhunthod P.,111 University Avenue | Thongbai P.,Khon Kaen University
Journal of the European Ceramic Society | Year: 2015

A novel strategy to improve the dielectric properties of CaCu3Ti4O12 ceramics was proposed by co-doping with Sm3+ and Mg2+. Sm3+ substituted in Ca2+ sites can effectively suppress the grain growth, achieving a fine grained ceramic microstructure. Mg2+ was selected to be substituted into Cu2+ sites to enhance the grain boundary (GB) resistivity for reducing the loss tangent (tanδ). High dielectric permittivity ε'≈1.25×104 and low tanδ≈0.039 at 1kHz were successfully accomplished in a Ca0.925Sm0.05Cu2.70Mg0.30Ti4O12 ceramic. Non-Ohmic properties were also enhanced. A slight increase in Ti3+/Ti4+ ratio in (Sm+Mg) co-doped CaCu3Ti4O12 ceramics was confirmed by the X-ray absorption near edge structure. Changes in tanδ values for all the co-doped ceramics were very consistent with their variations in GB resistance. The dielectric and non-Ohmic properties of co-doped ceramics were significantly improved by tuning both the geometric and intrinsic factors, i.e., increasing the density of GB layer and enhancing the GB resistance, respectively. © 2015 Elsevier Ltd.

Klysubun W.,111 University Avenue | Sombunchoo P.,111 University Avenue | Deenan W.,111 University Avenue | Kongmark C.,111 University Avenue
Journal of Synchrotron Radiation | Year: 2012

Beamline BL8 of the Synchrotron Light Research Institute (Thailand) is routinely operated for X-ray absorption spectroscopy (XAS) in an intermediate photon energy range (1.25-10 keV). The photon energy is scanned by using a double-crystal monochromator, the crystal pair of which can be interchanged among KTP(011), InSb(111), Si(111) and Ge(220). The experimental set-up conveniently facilitates XAS measurements in transmission and fluorescence-yield modes at several K-edges of elements ranging from magnesium to zinc. Instrumentation and specification of the beamline and the XAS station are described, together with the determination of the available photon flux [0.1-6 1010 photon s-1 (100 mA)-1], energy resolution (1-5 10-4) and stability of photon energy calibration (0.07 eV), representing the beamline performance. Data quality and accuracy of XANES and EXAFS measured at BL8 are compared with those of other well established beamlines. A noted distinction of BL8 is its relatively high sensitivity for studying phosphorous, sulfur and chlorine in diluted systems and its maximum beam size of 14 mm (width) 1 mm (height), which is suitable for bulk characterization. © 2012 International Union of Crystallography Printed in Singapore-all rights reserved.

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